In recent years, the digitalization of the broadcasting system by the NLE (nonlinear editing) system has been promoted. In such a circumstance, the amount of digital data also tends to increase along with the increase of the image for high-definition TV. Taking MPEG-2 data as an example, data bit rates not lower than 100 Mbps is required to improve the quality of the digital data, whereas the data bit rate ranges from 4 to 8 Mbps in the commercially available DVD-video image.
Namely, since the data amount becomes ten times or more in terms of the disk capacity, the improvement of a data transfer rate is important also on the storage apparatus side.
For example, a system disclosed in Japanese Patent Laid-Open Publication No. 2001-313620 is reported as a publicly-known digital broadcasting system.
As shown in Japanese Patent Laid-Open Publication No. 2001-313620, the digital broadcasting system generally includes an authoring apparatus (editing apparatus) and a sending apparatus, and the editing apparatus includes an authoring unit which performs authoring and a content storage unit in which contents formed in digital data are stored.
The authoring unit includes an editing control device, a server and the like which are unique to each manufacturer. Usually, a storage apparatus is used as the content storage unit. In Japanese Patent Laid-Open Publication No. 2001-313620, one dedicated storage apparatus with the single configuration is used. The storage apparatus has high-speed RAID configuration or a high-speed interface such as a fiber channel interface and iSCSI, because a high I/O rate is required for data I/O between an authoring unit and storage apparatus.
In another well-known digital broadcasting system, plural editing apparatuses are connected to one storage apparatus in SAN environment to share the file. In the file sharing, an exclusive process is adopted so that other editing apparatuses cannot access the file when one editing apparatus is accessing the file which is of an editing object.
In still another well-known digital broadcasting system, the file sharing by use of an IP network is reported.
As described above, in the digital broadcasting system, the needs for sharing the digital data with the plural editing apparatuses have been grown, and the means for sharing the digital data has been reported.